如果行存在则更新，如果不基于 user_id 则插入

Question

用户可以通过我网站上的编辑表单来编辑他们的位置。

有些用户可能没有输入位置开始，所以我需要查询来创建一行并插入用户的 user_id 和用户名以及他们提交的位置数据。

在尝试 REPLACE INTO 和多个 INSERT 查询后，我遇到了困难，显然我没有做对。

我的代码；

    require("includes/common.php");

    if(empty($_SESSION['user'])) 
    {  
        header("Location: index.php"); 
        die("Redirecting to index.php"); 
    } 

$uid=$_SESSION['user']['id'];

$location_city = $_POST['location_city'];
$loctaion_county = $_POST['location_county'];
$loctaion_country = $_POST['location_country'];

// query
$sql = "UPDATE locations
        SET  location_county=?, location_city=?, location_country=?
        WHERE user_id=$uid";
$q = $db->prepare($sql);
$q->execute(array($location_county,$location_city,$location_country));
header("location: edit-account.php");

请注意，我尝试通过预先填充的隐藏字段将用户名和 user_id 传递到数据库表中，并在上面的代码中使用其他 POST 变量来插入该数据。

上面的代码可以正常工作，因为我在位置表中手动创建了一条用户记录，用于测试目的，方法是替换 location_city 中的值。

更新：存在两个继续选项，不关闭任何选项 - 1) 注册时在表格中创建条目，因此在编辑位置时无需插入不存在的行。 2) 如果新行不存在，则创建一个新行。

我的注册码

<?php 

    // First we execute our common code to connection to the database and start the session 
    require("includes/common.php"); 

    // This if statement checks to determine whether the registration form has been submitted 
    // If it has, then the registration code is run, otherwise the form is displayed 
    if(!empty($_POST)) 
    { 
        // Ensure that the user has entered a non-empty username 
        if(empty($_POST['username'])) 
        { 
            // Note that die() is generally a terrible way of handling user errors 
            // like this.  It is much better to display the error with the form 
            // and allow the user to correct their mistake.  However, that is an 
            // exercise for you to implement yourself. 
            die("Please enter a username."); 
        } 

        // Ensure that the user has entered a non-empty password 
        if(empty($_POST['password'])) 
        { 
            die("Please enter a password."); 
        } 

        // Make sure the user entered a valid E-Mail address 
        // filter_var is a useful PHP function for validating form input, see: 
        // http://us.php.net/manual/en/function.filter-var.php 
        // http://us.php.net/manual/en/filter.filters.php 
        if(!filter_var($_POST['email'], FILTER_VALIDATE_EMAIL)) 
        { 
            die("Invalid E-Mail Address"); 
        } 

        // We will use this SQL query to see whether the username entered by the 
        // user is already in use.  A SELECT query is used to retrieve data from the database. 
        // :username is a special token, we will substitute a real value in its place when 
        // we execute the query. 
        $query = " 
            SELECT 
                1 
            FROM users 
            WHERE 
                username = :username 
        "; 

        // This contains the definitions for any special tokens that we place in 
        // our SQL query.  In this case, we are defining a value for the token 
        // :username.  It is possible to insert $_POST['username'] directly into 
        // your $query string; however doing so is very insecure and opens your 
        // code up to SQL injection exploits.  Using tokens prevents this. 
        // For more information on SQL injections, see Wikipedia: 
        // http://en.wikipedia.org/wiki/SQL_Injection 
        $query_params = array( 
            ':username' => $_POST['username'] 
        ); 

        try 
        { 
            // These two statements run the query against your database table. 
            $stmt = $db->prepare($query); 
            $result = $stmt->execute($query_params); 
        } 
        catch(PDOException $ex) 
        { 
            // Note: On a production website, you should not output $ex->getMessage(). 
            // It may provide an attacker with helpful information about your code.  
            die("Failed to run query: " . $ex->getMessage()); 
        } 

        // The fetch() method returns an array representing the "next" row from 
        // the selected results, or false if there are no more rows to fetch. 
        $row = $stmt->fetch(); 

        // If a row was returned, then we know a matching username was found in 
        // the database already and we should not allow the user to continue. 
        if($row) 
        { 
            die("This username is already in use"); 
        } 

        // Now we perform the same type of check for the email address, in order 
        // to ensure that it is unique. 
        $query = " 
            SELECT 
                1 
            FROM users 
            WHERE 
                email = :email 
        "; 

        $query_params = array( 
            ':email' => $_POST['email'] 
        ); 

        try 
        { 
            $stmt = $db->prepare($query); 
            $result = $stmt->execute($query_params); 
        } 

        catch(PDOException $ex) 
        { 
            die("Failed to run query: " . $ex->getMessage()); 
        } 

        $row = $stmt->fetch(); 

        if($row) 
        { 
            die("This email address is already registered"); 
        } 

        // An INSERT query is used to add new rows to a database table.
        // Again, we are using special tokens (technically called parameters) to 
        // protect against SQL injection attacks. 
        $query = " 
            INSERT INTO users ( 
                username, 
                password, 
                salt, 
                email
            ) VALUES ( 
                :username, 
                :password, 
                :salt, 
                :email 
            ) 
        "; 

        // A salt is randomly generated here to protect again brute force attacks 
        // and rainbow table attacks.  The following statement generates a hex 
        // representation of an 8 byte salt.  Representing this in hex provides 
        // no additional security, but makes it easier for humans to read. 
        // For more information: 
        // http://en.wikipedia.org/wiki/Salt_%28cryptography%29 
        // http://en.wikipedia.org/wiki/Brute-force_attack 
        // http://en.wikipedia.org/wiki/Rainbow_table 
        $salt = dechex(mt_rand(0, 2147483647)) . dechex(mt_rand(0, 2147483647)); 

        // This hashes the password with the salt so that it can be stored securely 
        // in your database.  The output of this next statement is a 64 byte hex 
        // string representing the 32 byte sha256 hash of the password.  The original 
        // password cannot be recovered from the hash.  For more information: 
        // http://en.wikipedia.org/wiki/Cryptographic_hash_function 
        $password = hash('sha256', $_POST['password'] . $salt); 

        // Next we hash the hash value 65536 more times.  The purpose of this is to 
        // protect against brute force attacks.  Now an attacker must compute the hash 65537 
        // times for each guess they make against a password, whereas if the password 
        // were hashed only once the attacker would have been able to make 65537 different  
        // guesses in the same amount of time instead of only one. 
        for($round = 0; $round < 65536; $round++) 
        { 
            $password = hash('sha256', $password . $salt); 
        } 

        // Here we prepare our tokens for insertion into the SQL query.  We do not 
        // store the original password; only the hashed version of it.  We do store 
        // the salt (in its plaintext form; this is not a security risk). 
        $query_params = array( 
            ':username' => $_POST['username'], 
            ':password' => $password, 
            ':salt' => $salt, 
            ':email' => $_POST['email'] 
        ); 

        try 
        { 
            // Execute the query to create the user 
            $stmt = $db->prepare($query); 
            $result = $stmt->execute($query_params); 
        } 
        catch(PDOException $ex) 
        { 
            // Note: On a production website, you should not output $ex->getMessage(). 
            // It may provide an attacker with helpful information about your code.  
            die("Failed to run query: " . $ex->getMessage()); 
        } 

        // This redirects the user back to the login page after they register 
        header("Location: login.php"); 

        // Calling die or exit after performing a redirect using the header function 
        // is critical.  The rest of your PHP script will continue to execute and 
        // will be sent to the user if you do not die or exit. 
        die("Redirecting to login.php"); 
    } 

?>

Answer 1

如果您尝试插入新行，它应该是这样的；

$sql = "INSERT INTO locations
    SET location_county=?, location_city=?, location_country=?, user_id=?

当然，只有在用户第一次提交位置数据时才会执行此查询。在插入新行之前，还建议检查是否存在包含用户 ID 和用户名的行。

Answer 2

我已经设法解决了REPLACE INTO 遇到的问题，下面的最终代码供参考；

$user_id = $_POST['user_id'];
$username = $_POST['username'];
$location_city = $_POST['location_city'];
$loctaion_county = $_POST['location_county'];
$loctaion_country = $_POST['location_country'];

    // query
    $sql = "REPLACE INTO locations(user_id,username,location_city,location_county,location_country) VALUES('$_POST[user_id]','$_POST[username]',$location_city,'$location_county','$location_country')";
    $q = $db->prepare($sql);
    $q->execute(array($_POST[user_id],$_POST[username],$location_city,$locaion_county,$location_country));
    header("location: edit-account.php");